Time in Vietnam

Reunified Vietnam follows Indochina Time (ICT), which is seven hours ahead of UTC, ICT is used all year round as Vietnam does not observe daylight saving time. Vietnam shares the same time zone with Thailand, Cambodia, Christmas Island, Laos, and Western Indonesia.

Vietnam referenced ISO 8601 under in 1998 and then created its own standard TCVN 6398-1:1998.

History

• After Phủ Liễn Observatory was built, French Indochina announced all states (consisting of north-Vietnamese Tonkin, central-Vietnamese Annam, south-Vietnamese Cochinchina, as well as Cambodia, Laos and Chinese Guangzhouwan) were part of 104°17′17″E longitude east of Paris meridian 2°20′14″E, or 106°37′30″E from Greenwich Mean Time from 00:00, 1 July 1906 onward.
• In 1911, Metropolitan France adopted UTC 00:00 (the solar time of Greenwich) as its official time, and used it until 1940 (with UTC 01:00 used during the summers from 1916 to 1940), forcing French Indochina observed UTC 07:00 from 00:00, 1 May 1911.
• Following change in time zone of Vichy authorities, French Indochina was integrated to UTC 08:00 skipping 60 minutes at 23:00, 31 December 1942.
• The Empire of Japan occupied Vichy French Indochina fully. Indochinese regions thereafter followed Tokyo time zone (UTC 09:00), skipping 60 minutes at 23:00, 14 March 1945.
• By August General Uprising, the Fall of Empire of Vietnam and the Proclamation of Independence of the Democratic Republic of Vietnam, Provisional Uniform Government of the Democratic Republic of Vietnam took control, announcing UTC 07:00 as official time zone on 2 September 1945. Whilst, the then under-attack regions of Vietnam, Laos and Cambodia adopted UTC 08:00 and non-attacked regions (at the time and even after the 1954 Geneva Conference) adopted UTC 07:00 from April 1, 1947: Laos (part of Indochina) from 15 April 1954, Hanoi from October 1954, Haiphong from May 1955.
• Under control of State of Vietnam, South Vietnam adopted UTC 07:00 from 00:00, 1 July 1955.
• South Vietnam time zone was changed to UTC 08:00 from 23:00, 31 December 1959, passing 60 minutes.
• North Vietnam confirmed official UTC 07:00 from 1 January 1968.
• Following the Fall of Saigon in April–May 1975, reunified Vietnam then observes UTC 07:00 with Saigon (and other southern parts) delaying 60 minutes on 13 June 1975.

Time in French Indochina

Period in use	Time offset from GMT	Notes
Prior to 1 July 1906	UTC 07:06:40	Local mean time
1 July 1906 – 30 April 1911	UTC 07:06:30	106°37'30"E French Time
1 May 1911 – 30 December 1942	UTC 07:00	Standard Time Zone
31 December 1942 – 13 March 1945	UTC 08:00	Standard Time Zone
14 March 1945 – 1 September 1945	UTC 09:00	Tokyo Standard Time
2 September 1945 – Activation of Geneva Accords	UTC 07:00	Standard Time Zone

Time in North Vietnam

Period in use	Time offset from GMT	Notes
2 September 1945 – 31 March 1947	UTC 07:00	Hanoi Time Zone
1 April 1947 – Activation of Geneva Accords After the activation	No Standard Time UTC 07:00 for zone under peace UTC 08:00 for zone under attacking
1 January 1968 – 12 June 1975	UTC 07:00	Hanoi Time Zone

Time in South Vietnam

Period in use	Time offset from GMT	Notes
Activation of Geneva Accords – 30 June 1955	UTC 08:00	Saigon Standard Time
1 July 1955 – 31 December 1959	UTC 07:00	Saigon Standard Time
1 January 1960 – 12 June 1975	UTC 08:00	Saigon Standard Time

Time in Reunified Vietnam

Period in use	Time offset from GMT	Notes
13 June 1975 – now	UTC 07:00	Standard Time Zone

See also

• ASEAN Common Time (ACT)
• Indochina Time (ICT)
• Time in Cambodia
• Time in Laos
• Time in Thailand
• UTC 08:00
• UTC 09:00

Bibliography

• Trần Tiến Bình (2005), Lịch Việt Nam thế kỷ XX-XXI (1901–2100), Nhà xuất bản Văn hoá Thông tin, Hanoi.